DC Comics published one of the strangest comic books ever, Superman vs. Muhammad Ali in 1978 and reissued it last month. NPR's Glen Weldon interviewed journalist Chris Klimek about the matchup of the century. Here's the setup:

No sooner does reporter Clark Kent stumble across Muhammad Ali shooting hoops in Metropolis' "inner city ghetto" than an despotic alien named Rat'lar appears to talk intergalatic trash. Specifically, Rat'lar is Emperor of the warlike Scrubb race, and he challenges earth's champion to fisticuffs. If said Earth champion loses, Earth will be destroyed. If said champion wins, Earth will be spared.

The question: Who will be Earth's champion? Superman claims the right, but Ali points out — quite rightly — that Superman is a Kryptonian, not an Earthman. Rat'lar isn't having any of this Terran shilly-shallying — he's got minions to yell at, and that fist of his doesn't shake itself, after all — so he orders the two men to decide the issue by duking it out in 24 hours' time.